During El Niño, the ocean surface temperature in the eastern Pacific warms and this leads to droughts in the western tropical Pacific and floods in the eastern part.

This in turn has an impact on agriculture, economic activity and even human health.

The question is what impact will global warming have on ENSO - the weather cycle that brings us El Niño?

"This has been a really important question that scientists have been trying to address for over 20 years now but it's really remained a mystery," says Power, a climate scientist at the Bureau of Meteorology.

"We're pretty excited now to actually have a little bit of a breakthrough."

Power and colleagues looked at the latest generation of world climate models and found that climate change is expected to intensify El Niño's effects.

"Projections produced by the models indicate that global warming interferes with the impact that El Niño sea-surface temperature patterns have on rainfall," says Power.

"This interference causes an intensification of El Niño-driven drying in the western Pacific and rainfall increases in the central and eastern equatorial Pacific. "

Power says the research findings are robust because they were borne out by a range of climate models.

"When we get consistency across models that increases the confidence we have in that projection."

Impact on Australia

While ENSO is a phenomenon centred in the tropical Pacific, it affects the weather in other parts of the world via a series of atmospheric "chain reactions", which the latest research does not cover.

"What we have to do now is work out what that means for places like Australia," says Power.

"The hypothesis would be that El Niño's impact would be intensified but we really need to test that."

Dr Alex Sen Gupta from the Climate Change Research Centre at the University of New South Wales, welcomes the new research.

"This is a very interesting study," he says.

Sen Gupta says predicting ENSO is a scientific "holy grail" and has been hampered by conflicting results from climate models on how global warming will affect it.

Some climate models say ocean surface temperature variation will intensify, while say it will weaken.

"What this study is saying is that even though we don't know what the temperature is going to do, climate models are agreeing on what the rainfall is going to do," says Sen Gupta.

"It's already dry during El Niño in the west and it's going to be even drier than it would normally be today. And in the east, it's already wet during an El Niño but in the future we would expect for it to be even wetter than it is today."

He says the intensification of droughts and floods referred to in this study is in addition to the extreme weather predicted by IPCC reports.